The present invention relates to a pallet container for flowable or pourable substances, wherein the container is provided with a preferably cubic interior container that is made of plastic and is surrounded by a supporting frame while being fastened on a pallet. In its bottom region, one side wall of the inner container is provided with discharging fittings.
A pallet container of the above described type is disclosed in German Pat. No. 2,545,023. That plastic inner container is surrounded by a closed sheet metal jacket with welded-on bottom, with the sheet metal jacket, which completely encloses the inner container, being fastened to a wood pallet by means of fastening claws.
The known pallet containers have a number of drawbacks. For example, when a pallet container is surrounded by a sheet metal jacket, fill level monitoring is possible only to an insufficient degree although viewing openings are provided in the sheet metal jacket. A further drawback is that the condition of the inner container cannot be detected from the outside. Possible damage can be located only with difficulty and frequently only with a delay in time so that the damage produced by the fill material can be kept within limits only with difficulty.
Such container is normally equipped with a lower discharge and an upper fill opening. If, upon emptying the container, the user forgets to unscrew the upper fill opening, the external air pressure compresses, or deforms, the inner container. This often makes the inner container unfit for further use and creates the additional danger that the formation of folds in the inner container makes it susceptible to damage from the outer sheet metal jacket.
A further drawback of inner containers surrounded by a sheet metal jacket is their insufficient stackability. For reasons of economy, very thin sheet metal is employed for the outer jacket, thereby considerably reducing stackability. Although, assuming perfect conditions, e.g. no dents in the sheet metal walls, two to three pallet containers can be stacked on top of one another, it frequently occurs during generally very rough loading dock operations that the containers to be stacked are set down rather abruptly so that the lowermost container wall is dented and the entire stack is in danger of tipping over.
Additionally, pallet containers made of plastic are known which are inserted into a stackable grate-type box so as to enable a plastic container of such size to be manipulatable by means of a stacking vehicle. Such a container is disclosed, for example, in German Utility Model Patent No. 1,910,944. The manufacture of such grate-type boxes is relatively expensive and additionally has the drawback that the angle profile welded to the upper and lower circumferential grate edge has only insufficient bending and twisting strength and thus the stability of the entire grate-type box is insufficient. The preferably spot-welded wire grate, particularly in cubic inner containers, serves the primary purpose of supporting the side walls of the inner container against the pressure of the fill material and of preventing buckling and thus destruction of the inner container. However, the ability of the wire grate to absorb the forces emanating from the fill material depends to a great degree on the thickness of the wire and on the narrowness of the wire mesh so that sufficient strength can here be realized only with the use of considerably more material. Deformation of the wire grate and thus buckling of the side walls of the inner container under the filling pressure can be prevented here only to the extent permitted by the stiffness of the box frame which is made of angle profiles. Due to the large expenditures for material and money involved in the manufacture of such grate-type boxes, these containers cannot be used, for reasons of economy, as one-way containers.
Although this is possible in connection with the abovementioned pallet container having a closed jacket made of thin sheet metal, one drawback of the completely encased pallet container is that it is impossible to monitor in any way the fill level in the container, or the condition of the interior of the plastic inner container and additionally there is no possibility of direct access if the inner container is damaged and thus could produce leaks, for example by laying the container on its side, since the location of the leakage cannot be determined from outside.